A 2-Gb/s CMOS Integrating Two-Tap DFE Receiver for Four-Drop Single-Ended Signaling

A 2-Gb/s integrating decision-feedback equalization (DFE) receiver was implemented for a four-drop single-ended DRAM interface channel by using a 0.25- mum CMOS process. The receiver combines both DFE and integration operations in a single receiver circuit so that the DFE operation reduces the intersymbol interference and the integration operation reduces the high-frequency noise. The DFE operation was implemented by switching the capacitance values of the two output nodes of a differential integrator, depending on the previous decision data. A look-ahead scheme was used to reduce the DFE loop delay. A MUX-embedded D flip-flop was used in the look-ahead circuit to further reduce the DFE loop delay and latency. The DFE operation enhanced the voltage margins by 110% and 90% at the 2-Gb/s stubless channel and the 1.2-Gb/s stub series terminated logic channel, respectively. The chip area and the power dissipation of the proposed receiver chip were 220 times 120 mum2and 10 mW, respectively, at the data rate of 2 Gb/s.